Heat insulating material

ABSTRACT

A resin foam has a porosity (X) of not less than 80%, having a cell (L) with a cell diameter of not less than 1 μm and not more than 1000 μm, and a cell (S) with a cell diameter of not less than 0.01 μm and less than 1 μm. The resin foam is excellent in thermal insulation performance and environmental performance, further, to provide a non Freon thermal insulation foam material maintaining the excellent thermal insulation performance for a long period of time and not generating condensation easily.

RELATED APPLICATIONS

This is a §371 of International Application No. PCT/JP2009/054261, withan international filing date of Mar. 6, 2009 (WO 2009/110587 A1,published Sep. 11, 2009), which is based on Japanese Patent ApplicationNos. 2008-057544, filed Mar. 7, 2008, 2008-057545, filed Mar. 7, 2008,and 2008-199418, filed Aug. 1, 2008, the subject matter of which isincorporated by reference.

TECHNICAL FIELD

This disclosure relates to resin foams excellent in thermal insulationperformance and environmental performance, and to non Freon thermalinsulation foam materials capable of maintaining such thermal insulationproperties for a long period of time.

BACKGROUND

Resin foams typified by a rigid urethane foam, a flexible urethane foamand expanded polystyrene are being used as heat insulating materials ofhouses and the like, and they play a very important role in reducingenergies for cooling and heating under increasing energy conservationminds in recent years.

Such heat insulating materials exhibit excellent thermal insulationperformance generally by containing low thermal conductivity gas in avery small volume inside a resin foam.

As the low thermal conductivity gas in heat insulating materials in pastyears, chlorofluorocarbons (CFC) were widely used, but because CFC are asubstance destroying the ozone layer, in place of them,hydrofluorocarbons (HFC) and low molecular hydrocarbons such as butaneand propane have been being used (JP 2007-332203 A and WO 00/01761 A1).However, since HFC have a very large Global Warming Potential, and thelow molecular hydrocarbons are inflammable, there is arising a movementthat carbon dioxide of lower environmental load and more safety is used.

However, since carbon dioxide is inferior in thermal insulationperformance to HFC and low molecular hydrocarbons, to obtain thermalinsulation properties of excellent thermal insulation performance, it isnecessary to improve thermal insulation performance of foam itself.

In general, the thermal insulation performance of foam varies dependingon porosity (X) and bubble diameter except for low thermal conductivitygas contained inside. The larger the porosity (X) and the smaller thebubble diameter, the higher the thermal insulation performance isexhibited. In the conventional art, to make porosity (X) large, the onlymeasure was to make bubble diameter large, so there was a tendency thatthe thermal insulation performance became bad when more than a certainporosity (X).

Thus, in recent years, various studies have been done for controllingthe bubble structure of foam. Particularly in JP 2007-153964 A, it isshown that various bubble diameters can be produced by using a styreneresin as a base and two kinds of blowing agents (water and carbondioxide).

However, because the overall bubble size is large, no good thermalinsulation performance can be obtained. Since water is used as a blowingagent, it will be a technique hardly applicable to polyester resins thathydrolysis is concerned.

It could therefore be helpful to provide a resin foam excellent inthermal insulation performance and environmental performance, further,to provide a non Freon thermal insulation foam material maintaining theexcellent thermal insulation performance for a long period of time andnot generating condensation easily.

SUMMARY

We thus provide:

-   -   (1) A resin foam where a porosity (X) is not less than 80%,        having a cell (L) with a cell diameter of not less than 1 μm and        not more than 1000 μm, and a cell (S) with a cell diameter of        not less than 0.01 μm and less than 1 μm.    -   (2) The resin foam described in (1), wherein a number density of        the cell (L) is not less than 10²/mm² and not more than 10⁷/mm²,        and a number density of the cell (S) is not less than 10²/μm²        and not more than 10⁷/μm².    -   (3) The resin foam described in (1) or (2), wherein two peaks        are present in the cell size distribution, one peak thereof is        present in not less than 10 μm and not more than 500 μm, and the        other peak is present in not less than 0.01 μm and less than 1        μm.    -   (4) The resin foam described in any one of (1) to (3), which        includes a biodegradable polyester resin, and includes at least        one kind of resin selected from the group consisting of a        polyether-polylactic acid block copolymer, a polypropylene        resin, a methacrylic resin, an acrylonitrile-butadiene-styrene        resin, and a polyester resin different from the biodegradable        polyester resin.    -   (5) A heat insulating material including the resin foam        described in any one of (1) to (4), carbon dioxide gas and a        resin film, wherein the resin film is not more than 15        [mL/(m²·day·atm)] (23° C., 0% RH) in carbon dioxide gas        permeability, covering the resin foam and the carbon dioxide        gas.    -   (6) The heat insulating material described in (5), wherein a        concentration of the internal carbon dioxide gas covered by the        resin film is not less than 50% by volume.    -   (7) The heat insulating material described in (5) or (6),        wherein the carbon dioxide gas is derived from carbon dioxide of        a blowing agent.    -   (8) The heat insulating material described in (7), wherein the        carbon dioxide is carbon dioxide in a supercritical state.    -   (9) The heat insulating material described in any one of (5) to        (8), wherein the resin film includes a biodegradable polyester        resin.

The resin foam is excellent in thermal insulation performance andenvironmental performance. By using such a resin foam, it is possible toprovide a non Freon thermal insulation foam material capable ofmaintaining the thermal insulation properties for a long period of time.This heat insulating material can be suitably used particularly as a nonFreon thermal insulation foam material for building materials and homeappliances.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of the cross section of a resin foam.

FIG. 2 is a schematic view of the cross section of a heat insulatingmaterial.

FIG. 3 is a schematic view of the cross section of another heatinsulating material.

FIG. 4 is a SEM picture of the resin foam obtained by Example 7.

FIG. 5 is an enlarged view of (a) part of FIG. 4.

FIG. 6 is an enlarged view of (b) part of FIG. 5.

DESCRIPTION OF NUMBERS AND SYMBOLS

1 Resin film

2 Mixture of adhesive substance and carbon dioxide generating material

3 Resin foam

10 Cell (S)

20 Cell (L)

DETAILED DESCRIPTION

Our heat insulating material includes a resin foam with a porosity (X)of not less than 80%, carbon dioxide gas, and a resin film having aspecified carbon dioxide gas permeability, and has a structure that theresin film covers the resin foam and carbon dioxide gas. Eachconstitution of the heat insulating material is explained below.

Structure of Resin Foam

Regarding the resin foam used in a heat insulating material, it isimportant for the porosity (X) to be not less than 80%. When theporosity (X) of resin foam is less than 80%, heat transmission by aresin in the foam becomes large, thus it is not preferable because theretends to pose a problem on the point of thermal insulation properties orthe like, when the resin foam is used in a heat insulating material.From the point of effectively suppressing heat transmission of the resinin the foam, the porosity (X) of resin foam is preferably not less than90%, and more preferably not less than 93%. When the porosity (X)exceeds 99%, strength of resin foam lowers, handling becomes difficult,thus the porosity (X) is preferably not more than 99%.

Additionally, as the calculation method of porosity (X), for example,there are listed a method that a cross section of foam is observed witha microscope or the like, the bubble part and resin part are analyzed byan image analyzing apparatus or the like, for calculation, and a methodof calculation from the specific gravity of resin before blowing and thespecific gravity of foam after blowing.

As the bubble structure of resin foam, there are an open-cell structurethat babbles are brought together, and a closed-cell structure thatbabbles are independent, but in the case of aiming at higher thermalinsulation performance, a resin foam having closed-cells is preferable.

Regarding the resin foam used in a heat insulating material, when itscross section is observed with a microscope or the like, for example, asshown in FIG. 1, it has a large cell (L) with a cell diameter of notless than 1 μm and not more than 1000 μm, and a small cell (S) with acell diameter of not less than 0.01 μm and less than 1 μm. Since cell(L) of a large cell diameter and cell (S) of a small cell diameter arecoexistent, the resin foam can achieve the porosity as described above,and also enhance thermal insulation performance.

When the cell diameter of cell (L) exceeds 1000 μm, there arisessometimes a problem that heat transmission due to convection andradiation of gas present in a cell becomes large. To effectivelysuppress heat transmission of gas in a cell, it is preferable to have acell of not less than 10 μm and not more than 500 μm, above-all, it ispreferable to have a cell of not less than 10 μm and not more than 100μm.

A high porosity (X) is achieved by a cell (L) of large cell diameter,and a minute cell (S) of submicron or nano-order is present in the wallsurface of the cell (L), thereby it becomes possible to greatly reduceheat transmission of the resin of wall surface. The smaller the cell(S), the cell can be present in the thinner wall surface, thus the cell(S) is preferably less than 1 μm. When the cell (S) is less than 0.01μm, there is a case that it becomes difficult to achieve to a highporosity (X). Therefore, as the cell (S), it is preferable to have acell with a cell diameter of not less than 0.01 μm and less than 1 μm.Further, it is preferable to have a cell with a cell diameter of notless than 0.05 μm and less than 1 μm, above all, it is preferable tohave a cell with a cell diameter of not less than 0.10 μm and less than1 μm.

Additionally, a cell diameter means an equivalent diameter circle, andthe equivalent diameter circle means a diameter of a circle having thesame area as the area of a cell.

In the resin foam, it is preferable that a number density of cell (L) isnot less than 10²/mm² and not more than 10⁷/mm², and a number density ofcell (S) is not less than 10²/μm² and not more than 10⁷/μm². By doingso, it becomes possible to form a minute cell (S) around the cell (L),it is possible to more heighten the porosity, and it becomes possible togreatly reduce heat transmission of resin. It is more preferable that anumber density of cell (L) is not less than 10³/mm² and not more than10⁷/mm², and a number density of cell (S) is not less than 10³/μm² andnot more than 10⁷/μm². It is preferable that the cell (L) and cell (S)are uniformly scattered in the resin foam.

As the resin foam, in the cell size distribution that is measured asexplained in the section of Example, a Bimodal distribution ispreferable. Ordinarily, the cell diameters of resin foam are not all thesame cell diameter, but present with a distribution in a certain range.The Bimodal distribution represents “a bimodal distribution ofsplit-peak type” where the distribution is present as two independentdistributions, or “a bimodal distribution of shoulder-peak type” wheretwo distributions are overlapped appearing two peaks. A preferabledistribution of the cell (L) and cell (S) is so-called “a bimodaldistribution of split-peak type,” the preferable peaks are in a range ofnot less than 10 μm and not more than 500 μm as the cell (L), and in arange of not less than 0.01 μm and less than 1 μm as the cell (S).

Production Method of Resin Foam

The production method of the resin foam as described above is notparticularly restricted, and there can be listed a method that in afinely dispersed mixture of a resin C with a resin D having a differenceof solubility of a blowing agent in a range of more than 0% and lessthan 5%, the blowing agent is impregnated for blowing (hereinaftercalled “method 1”), a method that in a finely dispersed mixture of aresin A with a resin B having a difference of solubility of a blowingagent, in a range of not less than 5%, the blowing agent is impregnatedfor blowing, then, the resin B is decomposed (hereinafter called “method2”), and the like.

First, “method 1” of the former is explained. This method is a methodthat cell (L) and cell (S) are produced by the solubility differencebetween island components and sea components uniformly dispersed innano-order (specifically, more than 0% and less than 5%).

The resin C and resin D used in the production method of this resin foamare not particularly restricted, and there are listed a polyurethaneresin, polystyrene resin, polypropylene resin, polylactic acid resin,polyester resin, polyethylene resin, methacrylic resin, polycarbonateresin, acrylonitrile-butadiene-styrene resin, and the like.Particularly, in the case of giving greater importance to environmentalperformance, a polylactic acid resin as resin C, and the above-describedother resin as resin D are preferably used.

The polylactic acid resin indicates a polylactic acid resin obtained byring-opening polymerization of lactide or direct polymerization oflactic acid, and a polylactic acid copolymer obtained by ring-openingpolymerization of lactide. In particular, a mixture of a polylactic acidcopolymer that lactide was subjected to ring-opening polymerization withpolyol and a polylactic acid resin is suitably used as a combination ofthe above-described resin C and resin D, and when it is a finelydispersed mixture where a distributed domain of polyol is less than 1μm, it is more preferable as a combination of the resin C and resin D.

Additionally, being finely dispersed indicates that the sea componentcomposed of the resin dispersed is less than 1 μm in diameter. As ameans for finely dispersing resin C and resin D, there are listed amethod that resin C and resin D are block-copolymerized, and the blockcopolymer is used as resin C and resin D, and a method that a blockcopolymer composed of resin C and resin D is added to resin C and resinD to improve compatibility between resin C and resin D. By changing themolecular weight and copolymerization ratio of a block copolymer used inthe above method, the effect can be more efficiently exhibited.Particularly in a block copolymer, by increasing the copolymerizationratio of sea components, the sea components tend to be fixed in space,so the localization of sea components can be suppressed, and a moreminute and uniform dispersion state is easily produced.

From such a point, as the resin particularly preferably used in “method1,” it is preferable to combine a polylactic acid resin as resin C, andas resin D, with one kind of resin selected from a polylactic acid blockcopolymer, polypropylene resin, polylactic acid resin different fromresin C, methacrylic resin and acrylonitrile-butadiene-styrene resin.

As the above-described polylactic acid block copolymer, as long as ithas a polylactic acid segment, other component is not particularlylimited, but a polyether-polylactic acid copolymer is preferably used.As the polyether component of the polyether-polylactic acid copolymer,an alkylene ether such as polyethylene glycol is suitably used, but itis not particularly limited. As a specific example of thepolyether-polylactic acid copolymer, an ABA type block copolymerobtained by ring-opening polymerization of lactide with polyethyleneglycol is listed. It is preferable that the molecular weight ofpolyethylene glycol is 2000 to 10000, and the molecular weight ofcopolymerized polylactic acid segment is 2000 to 3500.

Subsequently, “method 2” is explained. In this method, after cell (L) isproduced by resin A with high solubility of a blowing agent, resin Bwith low solubility of a blowing agent is decomposed, thereby to producecell (S).

The resin A used for blowing is not particularly restricted, the sameresin as in the foregoing “method 1” (resin C and resin D) can belisted. Namely, as the resin A, there are listed a polyurethane resin,polystyrene resin, polypropylene resin, polyester resin, polylactic acidresin, polyethylene resin, methacrylic resin, polycarbonate resin,acrylonitrile-butadiene-styrene resin, and the like.

On the other hand, as the resin (B), there are listed a polyester resin,methacrylic resin, or hydroxycarboxylic acids typified by polylacticacid resin and a biodegradable resin mainly consisting of aliphaticpolyesters. Particularly in the case of giving greater importance toenvironment, a biodegradable resin is preferable.

Blowing in the “method 1” and “method 2” is not particularly restricted,for example, it is conducted by the following method. Namely, there arean extrusion blowing process that a resin is supplied to an extruder orthe like, equipped with an injection apparatus of a blowing agent,heated to melt, after a blowing agent is injected or added according toneed, extruded into air through a slit die, or into a mold, the blowingagent is evaporated from the resin by a rapid pressure release at thattime to produce foam; a batch foaming process that after a resin is onceprocessed in a bead or sheet, the resin is charged together with ablowing agent into a pressure-resistant container such as autoclave, theblowing agent is impregnated in the resin at a predeterminedtemperature, pressure and time, foam is produced by a rapid pressurerelease or reheating after the impregnated resin is cooled, and thelike. By these processes, cell (L) and cell (S) are produced by “method1,” and cell (L) is produced by “method 2.”

In the case of “method 2,” subsequently, decomposition of resin (B) isconducted. As the decomposition of resin (B), photolysis, hydrolysis,thermal decomposition, decomposition with acid or alkali, decompositionby ultraviolet radiation, biodegradation by microbe or the like arelisted and, according to a resin to be decomposed, various methods canbe used. For example, when a resin to be decomposed ispolymethylmethacrylate, it can be decomposed by irradiating violet lightto a resin foam, and when polylactic acid, it can be decomposed byhydrolysis or biodegradation by microbe.

As a specific production example of resin foam by “method 2,” there arelisted a method that after polylactic acid and polymethylmethacrylateare mixed and blown to produce cell (L), the polymethylmethacrylate isdecomposed with a solvent dissolving only polymethylmethacrylate(toluene-hexane solution, or the like) to produce cell (S) around thecell (L), and a method that after polystyrene and polylactic acid aremixed and blown to produce cell (L), cell (S) is produced around thecell (L) by hydrolyzing only polylactic acid.

As the blowing agent used in “method 1” and “method 2,” a chemicalblowing agent that generates various gases by thermal decomposition, ora physical blowing agent using various gases themselves is listed. Inextrusion blowing, both chemical blowing agent and physical blowingagent can be suitably used, and in a batch foaming process, using aphysical blowing agent is preferable.

As the chemical blowing agent, mainly there are listedoxybis(benzenesulfonyl hydrazide) (OBSH), azodicarboxamide (ADCA),dinitroso-pentamethylene tetramine (DPT), sodium hydrogen carbonate,sodium carbonate, ammonium carbonate, potassium hydrogen carbonate,potassium carbonate, calcium hydrogen carbonate, calcium carbonate,magnesium carbonate and the like, among these, they can be used in onekind or a mixture of two kinds or more. In particular, sodium hydrogencarbonate is suitably used. For the purpose of accelerating thegeneration of carbon dioxide gas, an acidic agent such as potassiumhydrogen tartrate, calcium primary phosphate, fumaric acid and sodiumphosphate can be concomitant use with a carbon dioxide generatingmaterial.

As the physical blowing agent, butane, propane, nitrogen, carbon dioxidegas and the like are suitably used. However, since butane and propaneare inflammable, in the case of giving greater importance to safety andenvironmental performance, nitrogen and carbon dioxide gas arepreferable, and more suitably, carbon dioxide gas is used. As thephysical blowing agent, carbon dioxide can be used in a supercriticalstate or gas state. In the case of extrusion blowing process forproducing a resin foam, the inside of an extruder becomes a hightemperature and high pressure state, thus it is preferably used in asupercritical state where diffusion is fast and density is large, and inthe case of batch foaming, both the supercritical state and gas statecan be suitably used.

In the resin foam, a lubricant to provide stable performance ofextrusion and a particle such as a foam nucleating agent can be added ina range not damaging the effect. Specifically there are listed talc,silica, calcium silicate, wollastonite, kaolin, clay, mica, zinc oxide,titanium oxide, calcium carbonate montmorillonite, zeolite, sodiumstearate, magnesium stearate, barium stearate, fluid paraffin, olefintype wax, erucic acid amide and the like.

For the purpose of reflecting radiation heat or heat ray (far-infraredray) of sun light, or for the purpose of shielding a resin foam fromexternal air, it is also preferable to form a layer of metal or metaloxide over a part of resin foam or the whole surface.

As such metal, it is not particularly limited, aluminum, indium, zinc,gold, silver, platinum, nickel, chromium and the like are listed, and asthe metal oxide, oxides of titanium, zirconium, silicon, magnesium orthe like are listed. In particular, aluminum and indium with a highreflection effect of heat ray (far-infrared ray) are preferable, aboveall, aluminum with low gas permeability being widely used is mostpreferably used.

As the method for forming a layer of metal or metal oxide on the surfaceof resin foam, a method of depositing metal or metal oxide directly onthe foam and the like are listed. Constitution of resin film havingspecified carbon dioxide gas permeability, and production method thereof

Regarding the resin film used in a heat insulating material, ofimportance is that it is a resin film having specified carbon dioxidegas permeability, specifically, it is a resin film of not more than 15[mL/(m²·day·atm)] in carbon dioxide gas permeability at 23° C. and 0%RH. When the carbon dioxide gas permeability at 23° C. and 0% RH is morethan 15 [mL/(m²·day·atm)], the lowering of thermal insulationperformance due to gas dissipation of carbon dioxide gas is large, andit becomes difficult to maintain sufficient stable performance ofinsulation property particularly as building material applications.

The resin film is preferably not more than 5.0 [g/(m²·day)] in watervapor permeability at 40° C. and 90% RH. When the water vaporpermeability at 40° C. and 90% RH is more than 5.0 [g/(m²·day)], thermalinsulation performance lowers due to invasion of humidity inside thefoam, and it becomes difficult to maintain sufficient stable performanceof insulation property. Being dependent on use applications, there is apossibility that a trouble due to condensation takes place.

In the case of maintaining the thermal insulation performance for alonger period of time, it is preferable that the carbon dioxide gaspermeability is preferably not more than 10 [mL/(m²·day·atm)], and thewater vapor permeability is 0.8 [g/(m²·day)]. On the other hand, theless the carbon dioxide gas permeability and the water vaporpermeability are, the better, but as the lower limit, it is thought thatthe carbon dioxide gas permeability is about 0.01 [mL/(m²·day·atm)], andthe water vapor permeability is about 0.01 [g/(m²·day)].

Additionally, the carbon dioxide gas permeability is measured on thebasis of a gas chromatographic method described in JIS K7126-2 (2006),and the water vapor permeability is measured on the basis of an infraredcensor method described in JIS K7129 (2008).

Hereinafter, a resin film of not more than 15 [mL/(m²·day·atm)] incarbon dioxide gas permeability is called a carbon dioxide gas barrierfilm, and a resin film of not more than 15 [mL/(m²·day·atm)] in carbondioxide gas permeability and of not more than 5.0 [g/(m²·day)] in watervapor permeability is called a carbon dioxide gas/water vapor barrierfilm.

As the method for producing a carbon dioxide gas barrier film, there arelisted a method that a film is made of a resin with a high carbondioxide gas barrier property (hereinafter called “method A”), a methodthat a vapor metallized layer is provided on a film made of common resinto obtain a vapor metallized film (hereinafter called “method B”), andthe like.

The above-described “method A” is explained.

As the resin with a high carbon dioxide gas barrier property, a resinthat interaction between polymer main chains is strong and free volumeis small, such as polyvinyl alcohol, polyvinylidene chloride andpolyglycol acid, is preferably used. Above all, from industrializationand easiness in processing and availability, an ethylene-vinyl alcoholresin is preferably used.

As long as it is a film that the foregoing resin is used, anyfilm-forming method exhibits a high carbon dioxide gas barrier property,and when a film obtained by a resin with a high carbon dioxide gasbarrier property is drawn and orientated in one direction or twoperpendicular directions to be an oriented film, barrier properties ofcarbon dioxide gas and water vapor are further improved. This is becausewhen drawn and orientated, resulting from increase in regularity ofpolymer main chains themselves, interaction is strengthened and freevolume becomes small.

As the method for drawing and orientation, there are listed a sequentialbiaxial orientation that after drawing in one direction by passingthrough rolls provided with speed difference, both ends of film are heldat grips on a rail expanding toward the width direction, and drawing isdone in the width direction of film, and a simultaneous biaxialorientation that a film is drawn simultaneously in the longitudinaldirection and the width direction by internal pressure of film blown upin a tubular shape.

The layer constitution of a resin film in “method A” is not particularlyrestricted as long as there is at least one layer made of a resin with ahigh carbon dioxide gas barrier property. However, to further improvethe carbon dioxide gas barrier property, it is preferable to laminate avapor metallized layer on a resin film with a high carbon dioxide gasbarrier property being made of the foregoing resin.

Next, “method B” is explained.

As a common resin, there can be used a polystyrene resin, polyethyleneresin, polypropylene resin, polylactic acid resin, an aliphaticpolyester resin such as polybutylene succinate, an aromatic polyesterresin such as polyethylene terephthalate, a methacrylic resin,polycarbonate resin, polyamide resin, and the like. In particular, inthe case of aiming at a barrier film of low environmental load, thereare listed a polylactic acid resin, an aliphatic polyester resincomposed of aliphatic dicarboxylic acid and aliphatic diol, or apolyester resin composed of hydroxydicarboxylic acid is preferably used.Specifically, polybutylene adipate, polybutylene succinate, apolybutylene adipate/succinate copolymer, polyhydroxylactic acid,polycaprolactone, polylactic acid, polyglycol and the like. There can besuitably used a copolymer of aliphatic polyester and aromatic polyester,such as poly(butylene succinate-terephthalate) and poly(butyleneadipate-terephthlate), and a copolymer of aromatic polyesters such aspoly(butylene terephthalate-ethylene terephthalate) as well. In the caseof aiming at a heat insulating material of Carbon Neutral, a resinderived from biological resources (bioplastic) is preferably used, andin the case of giving greater importance to costs and easiness inprocessing and availability, polystyrene, polyethylene, polypropylene,polylactic acid and polyethylene terephthalate are preferably used.

The film-forming method of a common resin film is not particularlyrestricted, there are listed a melt film-forming process that a resinmelted by an extruder is casted on a mirror-surface drum to form a film,and a solution film-forming process that a resin is dissolved with asolvent, the solution is flown in planar shape, and then the solvent isevaporated to form a film. Above all, a melt film-forming process ispreferable from the points of costs and less environmental influence dueto solvent. In the same way as the “method A,” it is preferable that acommon resin film obtained is drawn and orientated in one direction ortwo perpendicular directions.

The layer constitution of a common resin film itself in “method B” maybe a single layer or lamination layer, and is not particularlyrestricted as long as it is a film composed of the above-describedcommon resin. However, because a common resin film alone cannot satisfythe carbon dioxide gas barrier property sufficiently, it is preferableto laminate a vapor deposition film of metal or metal oxide on at leastone surface of film to be a vapor metallized layer film. By doing so,the carbon dioxide gas barrier property is improved.

Although even one layer of the vapor metallized layer has a sufficientcarbon dioxide gas barrier property, in the case of obtaining a highercarbon dioxide gas barrier property, or aiming at preventing thelowering of local barrier property due to pinhole, two or more layers ofthe vapor metallized layer can be laminated. The more the vapormetallized, layers are laminated, it is preferable because the carbondioxide gas barrier property is improved, but which leads to an increasein cost and the lowering of productivity, thus the lamination layer ispreferably not more than 10 layers.

To produce a carbon dioxide gas/water vapor barrier film by setting thewater vapor permeability in a carbon dioxide gas barrier film to notmore than 5.0 [g/(m²·day)] or less, it is preferable to laminate apolyolefin resin film on a carbon dioxide gas barrier film produced by“method A” or “method B.”

Specifically, it may be enough to be a film that a layer composed of aresin where interaction between polymer main chains is strong and freevolume is small such as polyvinyl alcohol, polyvinylidene chloride andpolyglycol, and on at least one surface thereof, a layer of polyolefinresin such as polypropylene and polyethylene is laminated. A polyolefinresin is generally excellent in water vapor barrier property, thus bylaminating it on a carbon dioxide gas barrier film, a film withexcellent barrier properties for both carbon dioxide gas and water vaporcan be obtained.

As a specific film-forming method of such a carbon dioxide gas/watervapor barrier film, there are listed a method that while each of resinsis melted using two or more extruders, the resins are flown together soas to be a laminated structure, then, casted on a mirror-surface drum,and a method that the carbon dioxide gas barrier film and a polyolefinresin film separately film-formed are bonded with a binding agent or thelike in a separate process.

The laminated constitution in the carbon dioxide gas/water vapor barrierfilm is not particularly restricted. However, for enhancing a watervapor barrier property, as described above, it is preferable to providea vapor deposition layer of metal or metal oxide.

Hereinafter, a vapor deposition layer in a carbon dioxide gas barrierfilm or a carbon dioxide gas/water vapor barrier film is detailed.

As the metal used in the vapor deposition layer, there are listedaluminum, indium, zinc, gold, silver, platinum, nickel, chromium and thelike. As the metal oxide used in the vapor deposition layer, there arelisted an oxide of titanium, zirconium, silicon, magnesium and the like.Among these, aluminum with low permeation properties of carbon dioxidegas and water vapor being widely used is suitably used. By forming thevapor deposition layer on a resin film, barrier properties of carbondioxide gas and water vapor are improved, and this is suitably used as acarbon dioxide gas barrier film or a carbon dioxide, gas/water vaporbarrier film.

As the vapor deposition method of metal or metal oxide, it is possibleto use a physical vapor deposition technique such as vacuum evaporation,Electron Beam evaporation, sputtering and ion-plating, and a chemicalvapor deposition technique such as plasma-enhanced Chemical VaporDeposition, and from the viewpoint of productivity, vacuum evaporationis particularly preferably used.

In laminating a vacuum deposition layer, for improving adhesion ofvacuum deposition layer, it is preferable to previously conductpretreatment such as corona discharge treatment on the surface to bedeposited of a resin film as a base material.

Additionally, in the case that the desired carbon dioxide gas barrierproperty and water vapor barrier property are not obtained even by theabove, a plurality of vapor deposition films with the same constitutionor different constitution may be stuck. When the purpose is to preventgas leak from the foam when used in a heat insulating material, it ispreferable to stick two pieces or more.

In forming a vapor deposition layer, it is also preferable to coat aprimer on a film as a base material previously in line or off line.Providing a coated layer of primer is preferable because a vapordeposition layer of high adhesion is obtained, which is effective forimproving barrier properties of carbon dioxide gas and water vapor.

Further, in a resin film, a particle such as lubricant and foamnucleating agent can be added in a range not damaging the effect.Specifically there are listed talc, silica, calcium silicate,wollastonite, kaolin, clay, mica, zinc oxide, titanium oxide, calciumcarbonate montmorillonite, zeolite, sodium stearate, magnesium stearate,barium stearate, fluid paraffin, olefin type wax, erucic acid amide andthe like.

Carbon Dioxide Gas

In the heat insulating material, including carbon dioxide gas isimportant.

As long as carbon dioxide gas is included in the heat insulatingmaterial, origin (origination) of the carbon dioxide gas is notparticularly restricted, for example, there are listed (1) carbondioxide gas derived from carbon dioxide in a supercritical state of ablowing agent, (2) carbon dioxide gas derived from biodegradable resinand microbe, (3) a carbon dioxide generating material is contained in aheat insulating material, carbon dioxide gas derived from the carbondioxide generating material, and the like.

In regard to (1), in producing a resin foam that is used in a heatinsulating material, a resin foam is produced using carbon dioxide in asupercritical state as a blowing agent, the resin foam containing thecarbon dioxide is covered with the above-described resin film such as acarbon dioxide gas/water vapor barrier film to produce a heat insulatingmaterial, thereby carbon dioxide gas can be included in the heatinsulating material.

In regard to (2), for producing a heat insulating material, in coveringa resin foam using the above-described resin film such as a carbondioxide gas/water vapor barrier film, by covering a biodegradable resinand microbes as a carbon dioxide generating material at the same time,carbon dioxide gas can be included in the heat insulating material.Regarding the biodegradable resin as one of the carbon dioxidegenerating material, a biodegradable resin typified by polycaprolactone,polybutylene succinate, polyethylene succinate and the like is listed.By conducting biodegradation using these resins and microbes, carbondioxide gas can be generated. In this regard, when a molecular weight ofbiodegradable resin is several ten thousands or more, since there is acase that biodegradation is difficult to occur, the molecular weight ofbiodegradable resin is 50000 or less in number-average molecular weight,and preferably 10000 or less. The lower limit of the number-averagemolecular weight is about 1000.

In regard to (3), for producing a heat insulating material, in coveringa resin foam using the resin film such as a carbon dioxide gas/watervapor barrier film, by covering a carbon dioxide generating materialwith the resin film at the same time, carbon dioxide gas generating fromthe carbon dioxide generating material can be included in a heatinsulating material. As the carbon dioxide generating material, there islisted at least one kind selected from the group consisting of sodiumhydrogen carbonate, sodium carbonate, ammonium carbonate, potassiumhydrogen carbonate, potassium carbonate, calcium hydrogen carbonate,calcium carbonate and magnesium carbonate, and carbon dioxide gasderived from these can be used.

Heat Insulating Material

The heat insulating material includes the resin foam, carbon dioxide gasand resin film as described above, and constitution that the resin foamand carbon dioxide gas are covered with the resin film is preferable.Further, the inside covered with the resin film can include a carbondioxide generating material. Covering indicates that a resin foam andcarbon dioxide gas are closely sealed with a resin film, and its methodis arbitral.

The heat insulating material is specifically shown in FIG. 2 and FIG. 3.FIG. 2 is the cross sectional view of a heat insulating material. As amethod for producing the heat insulating material of FIG. 2, forexample, there is listed a method that a mixture of an adhesivesubstance and a carbon dioxide generating material is coated on thesurface of a resin film such as carbon dioxide gas/water vapor barrierfilm (in the case of using a carbon dioxide gas/water vapor barrier filmhaving a vapor deposition layer, resin surface of the carbon dioxidegas/water vapor barrier film) (hereinafter, in a carbon dioxidegas/water vapor bather film having a vapor deposition layer on onesurface, a surface not having a vapor deposition layer is called a resinsurface), thereby to stick a resin foam. There is also listed a methodthat a mixture of a low melting point polymer and a carbon dioxidegenerating material is coated on the surface of a resin film such ascarbon dioxide gas/water vapor barrier film (in the case of using acarbon dioxide gas/water vapor barrier film having a vapor depositionlayer, resin surface of the carbon dioxide gas/water vapor barrierfilm), thereby to conduct thermal adhesion to a resin foam.

As the specific example, there is listed a method that after polylacticacid of 20000 in number-average molecular weight is dissolved intetrahydrofuran (THF), the solution is uniformly coated on a resinsurface and heated by a hot-air dryer to sufficiently evaporate thesolvent, subsequently, an adhesive layer that microbes and starch weremixed is over-coated on the coated surface of polylactic acid, stuck toa resin foam, and ends of carbon dioxide gas/water vapor barrier film orthe like are subjected to thermal adhesion. There is also listed amethod that an adhesive mixture of starch and sodium hydrogen carbonateis produced, then, coated on the resin surface of carbon dioxidegas/water vapor barrier film or the like having a vapor depositionlayer, this is subjected to thermal adhesion to a resin foam that wasextrusion-blown. However, it is not limited thereto.

FIG. 3 is the cross sectional view of a heat insulating material. As amethod for producing the heat insulating material of FIG. 3, forexample, there is listed a method that after producing two sets ofconstituted bodies where the resin surface of a resin film such ascarbon dioxide gas/water vapor barrier film and one surface of resinfoam are melt-bonded, in one set of the two sets of constituted bodies,on the surface opposite to the side that the film was melt-bonded(hereinafter, resin foam surface), an adhesive layer that emulsion ofbiodegradable resin, microbes and starch were mixed is coated overall orpartly, and stuck to the resin foam surface of the other set.Alternatively, there is listed a method that after injecting a mixedliquid of emulsion of biodegradable resin and microbes into the insideof a resin foam with a syringe, the resin foam and a resin film such ascarbon dioxide gas/water vapor barrier film are melt-bonded. However, itis not limited thereto.

Additionally, other than the materials shown in FIG. 2 and FIG. 3, thereis listed a constitution that a resin foam and a carbon dioxidegenerating material are covered with a resin film using a method thatafter a resin film such as carbon dioxide gas/water vapor barrier filmis processed in a bag, in which a resin foam and a carbon dioxidegenerating material are put, and opening is sealed by melt-bonding, orwith a sticker or an adhesive.

There is also listed a method that even without containing a carbondioxide generating material, the whole surface of a resin foamcontaining carbon dioxide gas being blown with carbon dioxide gas iscovered with a resin film such as a carbon dioxide gas/water vaporbarrier film (in the case of carbon dioxide gas barrier film having avapor deposition layer, for the resin surface so as to be opposite to aresin foam), and a resin film run off from the four corners of the resinfoam is subjected to thermal adhesion with an impulse sealer.

To maintain thermal insulation performance for a long period of time, itis preferable to contain 50 volume % or more in concentration ofinternal carbon dioxide gas covered when the concentration of internalgases covered is 100 volume %. It is more preferably 70 volume % ormore, and further preferably 80 volume % or more.

Regarding the heat insulating material produced by the above-describedmethod, since the resin foam is covered with a resin film such as acarbon dioxide gas/water vapor barrier film, the lowering of thermalinsulation properties due to gas dissipation of carbon dioxide gas fromthe resin foam hardly takes place. In addition, in the case that acarbon dioxide generating material is present inside, because carbondioxide gas is generated from the carbon dioxide generating material, itis possible to maintain thermal insulation performance for a long periodof time.

Specifically, it is preferable for the heat insulating material to benot more than 30 (mW/mK) in thermal conductivity right after producing aheat insulating material, and further preferably not more than 25(mW/mK). Additionally, the less the thermal conductivity is, the morepreferable, but the lower limit practically achievable is thought to beabout 10 (mW/mK).

From the viewpoint of long-use (durability), the value of thermalconductivity after storage under high humidity or under high vacuum fora long period of time is also important. Specifically, the thermalconductivity of heat insulating material after storage for 250 hoursunder an environment at a temperature of 60° C. and a humidity of 85% RH(under high humidity environment) is preferably not more than 30(mW/mK), and further preferably not more than 25 (mW/mK).

Further, the thermal conductivity of heat insulating material afterstorage for 1000 hours under an environment at a temperature of 40° C.,a humidity of 0% RH and a vacuum of 300 Torr is preferably not more than35 (mW/mK), and further preferably 30 (mW/mK).

It becomes possible to exhibit the thermal conductivity described above.

In such a heat insulating material, water vapor from the outside of heatinsulating material is difficult to permeate. Therefore, when used inhouses and the like, it is suitable as a heat insulating material notgenerating condensation easily

Lastly, the heat transfer mechanism of resin foam commonly thought is,written below, and the principle is inferred:

λf (thermal conductivity of foam)=λg (thermal conductivity of gas infoam cell)+λs (thermal conductivity of resin in foam)+λc (convectiveheat transfer of gas in foam cell)+λr (radiant heat transfer in foamcell)   (Formula 1).

In the above formula, λg and λs are terms related to the porosity (X) offoam, λc and λr are terms related to cell diameter. Specifically, whenthe porosity (X) of foam increases, contribution of λg becomes large,and when the porosity (X) of foam decreases, contribution of λs becomeslarge. When cell diameter becomes large, contribution of λc and λrbecomes large, and when cell diameter becomes small, contribution of λcand λr becomes small.

Herein, the resin foam used in a heat insulating material has a largecell (L) with a cell diameter of not less than 1 μm and not more than1000 μm, and a small cell (S) with a cell diameter of not less than 0.01μm and less than 1 μm. In general, when a cell with the cell diameter ofnot more than 1000 μm, heat transfer of λc and λr becomes negligiblesmall, resulting from that a cell is generated on the resin wall surfacefoamed by cell (S), λs becomes small. As a result, it is thought toobtain a resin foam having high thermal insulation properties (lowthermal conductivity).

Examples (1) Porosity (X)

-   -   a) Using a scanning electron microscope (FE-SEM) manufactured by        JEOL Ltd., a cross section of resin foam was enlarged to a range        for the measuring image region of one side to be 500 μm, and an        image was scanned.    -   b) A transparent sheet (OHP sheet) was placed on a photograph,        and the part of cell was marked out thereon with black ink.    -   c) The image treated in b) by an image treating apparatus        (manufactured by Pierce Company, part number: PIAS-II) was        scanned, the dark color part and pale color part (whether marked        with black ink or not) were distinguished, using “FRACTAREA”        (area ratio) in the image analytical calculation function, the        area of dark color part, that is, the area of cell (Va) was        obtained, and porosity (X) was obtained by the following        formula:

Porosity (X)%=[area of whole image−area (Va)]/area of whole image×100.

-   -   d) The number of measuring samples was set to 5 (n=5), the        average of 5 times was defined as porosity (X).

(2) Porosity (X2)

It was calculated from specific gravity of resin before blowing (Gp) andspecific gravity of resin foam (Gf) using the following formula.Measurement of specific gravity was measured by an electronic hydrometer“SD-120L” available from Mirage Trading Company. The average of 5samples was used as specific gravity of resin foam (Gf).

Measuring Condition

-   -   Sample size: 3 cm square×1 cm thickness    -   Measuring water temperature: 23° C. (pure water was used)    -   Number of measuring samples: 5 (=n number)

Calculating Formula

Porosity (X2)=(1−Gf/Gp)×100 [%]

(3) Confirmation Method of Presence or Absence of Cell (L) and Cell (S),and Number Density

Using a scanning electron microscope (FE-SEM) manufactured by JEOL Ltd.,an image of the cross section in the thickness direction of resin foambeing enlarged by 100 times was scanned. Presence or absence of cell (L)was confirmed from the image. The number of bubbles of cell (L) wasmeasured from the image scanned. In this regard, when part of a bubblewas run off from screen, the bubble was not counted as the number ofbubbles. The number of bubbles measured was converted into the number ofbubbles per unit area (1 mm²) thereby to calculate a number density.This measurement was carried out randomly at 100 places, and the averagewas defined as the number density of cell (L).

Next, an image in the vicinity of cell (L) being enlarged by 20000 timeswas scanned. Presence or absence of cell (S) was confirmed from theimage. The number of bubbles of cell (S) was measured from the imagescanned. In this regard, when part of a bubble was run off from screen,the bubble was not counted as the number of bubbles. The number ofbubbles measured was converted into the number of bubbles per unit area(1 μm²) thereby to calculate a number density. This measurement wascarried out randomly at 100 places, and the average was defined as thenumber density of cell (S).

Additionally, the presence or absence of cell (L) was determined bypresence or absence of a cell of not less than 1 μm and not more than1000 μm in equivalent diameter circle, and the presence or absence ofcell (S) was determined by presence or absence of a cell of not lessthan 0.01 μm and less than 1 μm in equivalent diameter circle. Theequivalent diameter circle herein is a diameter of a circle having thesame area as the area of a cell. The equivalent diameter circle wasobtained by a cell cross-sectional area after the SEM image scanned bythe above-described magnification ratio was treated in the same way asthe foregoing (1) by an image treating apparatus (manufactured by PierceCompany, part number: PIAS-II). Namely, the cross-sectional area of thecell part marked black was able to be calculated by the image treatingapparatus, and a diameter of a circle having the same cross-sectionalarea as this cross-sectional area was defined as equivalent diametercircle.

(4) Average Cell Diameter of Cell (L) and Cell (S)

Using a scanning electron microscope (FE-SEM) manufactured by JEOL Ltd.,an image of the cross section in the thickness direction of resin foambeing enlarged by 100 times was scanned. From the image scanned, cellsof not less than 1 μm and not more than 1000 μm in equivalent diametercircle were chosen, and the average of the total numbers was defined asthe average cell diameter of cell (L).

Next, an image of bubble wall surface at the center being enlarged by10000 times was scanned. The image scanned was divided into 4 blocks onleft, right, top and bottom, cells of not less than 0.01 μm and lessthan 1 μm in equivalent diameter circle per one block were chosen, andthe average of the total numbers was defined as the average celldiameter of cell (S).

Using SEM images of 5 places per one sample of resin foam (n=5), theaverage of 5 times was defined as the average of cell (L) and cell (S).

(5) Cell Size Distribution of Resin Foam

The cross section in the thickness direction of resin foam was observedby a magnification ratio of Table 1 using a scanning electron microscope(FE-SEM) manufactured by JEOL Ltd. To make a cross section of resin foamvisible, a cross-section polisher (CP) method using argon ion beam wasused.

In each magnification ratio of a microscope shown in Table 1, cells of100 pieces were chosen randomly, the minor axis part (Ls) and major axispart (Ll) per one cell were measured in “two-point distance.” Theaverage of (Ls) and (Ll) was defined as an average cell diameter (La)nof one cell (where n=1 to 100), a histogram of the average cell diameter(La)n in each magnification ratio was drawn. Incidentally, like presenceat the edge of a SEM image, a cell that the whole length of celldiameter was unobservable was not measured.

Regarding the drawing of histogram, it was drawn in such a manner thatthe number of classes (pillars) was 10, and the width was calculated forthe value of (La)n to be not present in the border value of class(pillar).

In sampling a cell at each magnification ratio, double count of the samecell in measurement was avoided by setting the lower limit (or the upperlimit).

The histograms at each magnification ratio thus obtained were linked,which was defined as a cell size distribution.

In a curve that medians at each frequency in the cell size distributionwere linked, the medium in the frequency that the slope became a limitvalue, that is, the medium in the frequency that the slope of curve waschanged from positive to negative was defined as a peak.

TABLE 1 Microscope magnificationa Cell diameter to be measuredMagnification 50 times Cell diameter of not less than 100 μmMagnification 300 times Cell diameter of not less than 10 μm and lessthan 100 μm Magnification 3000 times Cell diameter of not less than 1μmand less than 10 μm Magnification 25000 times Cell diameter of not lessthan 0.5 μm and less than 1.0 μm Magnification 50000 times Cell diameterof not less than 0.1 μm and less than 0.5 μm Magnification 100000 timesCell diameter of less than 0.1 μm

(6) Measurement of Carbon Dioxide Gas Permeability and Water VaporPermeability of Resin Film

In the condition of a temperature at 23° C. and a humidity at 0% RH,based on a gas chromatographic method described in JIS K7126-2 (2006)),carbon dioxide gas permeability was measured using a gas permeabilitymeasuring apparatus (GL Science Inc.: GPM-250). The measurement wasconducted twice, and the average of two measured values was defined ascarbon dioxide gas permeability.

In the condition of a temperature at 40° C. and a humidity at 90% RH,based on an infrared sensor method described in JIS K7129 (2008), watervapor permeability was measured using a humidity transmission measuringapparatus (USA, MOCOM: “PERMATRAN-W3/31”). The measurement was conductedtwice, and the average of two measured values was defined as water vaporpermeability.

(7) Measurement of Thermal Conductivity

It was measured using a thermal conductivity measuring apparatus“TPS-2500” manufactured by Hot Disk Corporation. As the measuring place,5 places of a center part and four corners of a heat insulating materialwere measured, and each average was defined as thermal conductivity.

For the heat insulating material measured, after aging test was doneusing a constant temperature, constant humidity bath, and a vacuum ovenunder the following environment, thermal conductivity was measured onceagain.

Measuring Condition of Thermal Conductivity

-   -   Temperature: 23° C.    -   Humidity: 65% RH    -   Sensor: 7 mmφ (covered with polyimide)

Aging Test Condition

-   -   Aging test (1): temperature 60° C., humidity 85% RH, 250 hours    -   Aging test (2): temperature 40° C., humidity 0% RH, vacuum 300        Torr, 1000 hours

(8) Thermal Insulation Performance of Resin Foam Alone

Since a blowing agent in a production process remains in a resin foam,whose thermal insulation performance greatly varies dependent on thekind of blowing agent used. Thus, as the evaluation of thermalinsulation performance, the following pretreatment was conducted, and ablowing agent in a resin foam was completely replaced with air tomeasure thermal insulation performance. The measurement was done using athermal conductivity measuring apparatus “TPS-2500” manufactured by HotDisk Corporation. As the measuring place, 5 places of a center part andfour corners of a resin foam were measured, and each average was definedas thermal conductivity.

Measuring Condition of Thermal Conductivity

-   -   Temperature: 23° C.    -   Humidity: 65% RH    -   Sensor: 7 mmφ (covered with polyimide)

Pretreatment

-   -   a) A resin foam was placed in a desiccator, and vacuumed to 300        Torr at 23° C., and allowed to stand still for 10 hours.    -   b) Next, it was gradually returned to ambient pressure over 2        hours in air.

After the cycle of a) and b) was carried out 10 cycles, the resin foamwas taken out from the desiccator, and measurement of thermalconductivity was conducted.

(9) Condensation Test of Heat Insulating Material

-   -   (A) Condensation preventing performance was evaluated on the        basis of “condensation preventing performance test method of        fitting (JIS A1514).” Air temperature in a constant temperature        high humidity room and a low temperature room was set at 20° C.,        and relative humidity in a constant temperature high humidity        was set at about 40% RH, after confirmation that the temperature        of each part of heat insulating material came to equilibrium        sufficiently (confirm that the surface temperature of heat        insulating material is equilibrated sufficiently with air        temperature in a constant temperature high humidity),        temperature in the low temperature room was changed to 5° C. to        −10° C. by 5° C. intervals. The observation of condensation was        done in such a manner that after temperature measurement was        finished, relative humidity in the constant temperature high        humidity room was raised to 50% RH, the state was kept for 1        hour, and evaluated by naked eye. The evaluation was; o: cloudy,        Δ: small droplet (diameter of 1 mm or less), and ×: large        droplet (diameter exceeding 1 mm).    -   (B) As a wall condensation preventing test of a heat insulating        material, air temperature in a constant temperature high        humidity room and a low temperature room was set at 20° C., and        relative humidity in a constant temperature high humidity was        set at about 85% RH, after confirmation that the temperature of        each part of heat insulating material came to equilibrium        sufficiently (confirm that the surface temperature of heat        insulating material is equilibrated sufficiently with air        temperature in a constant temperature high humidity), the        temperature in a low temperature room was set at −5° C. The        observation of wall condensation was done in such a manner that        after temperature measurement was finished, relative humidity in        the constant temperature high humidity room was raised to 85%        RH, the state was kept for 1000 hours, then, presence or absence        of condensation inside the low temperature room of heat        insulating material was evaluated by naked eye. Namely, whether        water vapor in a constant temperature high humidity passes        through the heat insulating material to reach the low        temperature room side or not was determined by naked eye. The        surface of low temperature room side of heat insulating material        was evaluated as o: no generation of frost, and ×: generation of        frost.

Additionally, wall condensation means that in the case of providing awall of a building with a heat insulating material, condensation isgenerated resulting from that water vapor inside room passes through theheat insulating material, water vapor is cooled between the heatinsulating material and the wall surface of the building.

(10) Concentration of Carbon Dioxide Gas Inside Heat Insulating Material

It was analyzed/measured by a headspace gas analyzer equipped with GC/MSequipment. As the carrier gas, a helium gas of 99.8% purity in cylinderwas used.

-   -   (i) As a base line, a peak of helium of carrier gas was        detected, and the peak area (BPh) was calculated.    -   (ii) Next, a sampling needle was inserted by 5 cm or more in the        most longitudinal direction of a heat insulating material, 5 mL        of gas inside the heat insulating material was sampled.    -   (iii) The gas sampled was mixed with helium carrier gas, and        injected in a column of GC/MS equipment.    -   (iv) From MS analysis of gases separated by GC, peaks of helium,        nitrogen, oxygen, hydrocarbons and carbon dioxide were detected,        and each peak area (Ph), (Pn), (Po), (Phc) and (Pc) were        calculated.    -   (v) From the peak area obtained, concentration of carbon dioxide        gas inside the heat insulating material was calculated by the        following formula:

Carbon dioxide gas concentration [%]={Pc/(Ph−BPh+Pn+Po+Phc+Pc)}×100.

-   -   (vi) The number of measuring samples was set to 5 (n=5), and the        average of 5 times was defined as carbon dioxide gas        concentration.

(11) Carbon Dioxide Solubility in Each Resin

Using a magnetic suspension balance (MSB), under carbon dioxide gasatmosphere, the amount of carbon dioxide gas (g) dissolved in 1 g ofresin sample was measured. The number of measuring samples was set to 5(n=5), and the average of 5 times was defined as carbon dioxidegas-dissolved amount. Given that the weight impregnated with carbondioxide gas by the same weight as the resin sample weight is 100%,solubility (%) in each sample was calculated.

(12) Meaning of the Symbol in Table

-   -   Resin (A-1): Polylactic acid (weight-average molecular weight of        150000, L body of 96%)    -   Resin (A-2): Polymethylmethacrylate (manufactured by Mitsubishi        Rayon Co., Ltd., “Acrypet MF,” fluidity: 14 g/10 min, refractive        index=1.490)    -   Resin (A-3): Polyethylene glycol (manufactured by Sanyo Chemical        Industries, Ltd., “PEG-6000S,” number-average molecular weight        of 8300)    -   Resin (A-4): Polystyrene (manufactured by PS Japan Corporation,        “G9401,” MFR=2.2)    -   Resin (A-5): Polyether-polylactic acid block copolymer (produced        as follows: that is, in a sealed vessel equipped with a vacuum        line and a heating apparatus, 0.85 kg of polyethylene glycol        with a number-average molecular weight of 8,500 was charged,        after dehydration under reduced pressure at 140° C. for 30        minutes, 0.5 kg of L-lactide was charged. Next, the inside of        the vessel was replaced with inert gas, while polyethylene        glycol and L-lactide were melted and stirred, 10 g of tin (II)        2-ethylhexanate was added, and stirred under inert gas        atmosphere at 160° C. for 3 hours, then, 7.5 g of dimethyl        phosphate was added as a catalyst deactivating agent and stirred        for 30 minutes. Next, after stirring at 140° C. for 2 hours        under reduced pressure to remove a volatile substance, it was        returned to atmosphere pressure with inert gas, thereby        obtaining a polyether-polylactic acid block copolymer of 13,500        in molecular weight.)    -   Resin (A-6): Polymethylmethacrylate (manufactured by Sumitomo        Chemical Co., Ltd., “Sumipex MHF”)    -   Resin (A-7): Polypropylene (manufactured by Japan Polypropylene        Corporation, “Newfoamer”)    -   Resin (A-8): Acrylonitrile-butadiene-styrene resin (manufactured        by Toray Industries, Inc., “Toyolac 600”)    -   Fiber-based heat insulating material (GW-1): Glass wool        (manufactured by Asahi Fiber Glass Co., Ltd. “Mat Ace Plus”)    -   Blowing agent (F-1): Carbon dioxide gas (supercritical        penetration)    -   Foam nucleating agent (T-1): Talc (manufactured by Japan Talc        Co., Ltd., “SG-95,” average particle diameter of 2.5 μm)    -   Resin (B-1): Polyethylene terephthalate (manufactured by Mitsui        Chemicals, Inc., “Mitsui PET J120”)    -   Resin (B-2): Polybutylene terephthalate (manufactured by Toray        Industries, Inc., “1200S”)    -   Resin (B-3): Polyglycol acid (produced as follows: that is, 70%        glycol acid aqueous solution was heated at 180° C. under        nitrogen stream, thereafter, gradually vacuumed to 1.0×10⁻² MPa        to concentrate glycol acid. At the point when water of about 30        weight % relative to the amount of glycol acid aqueous solution        was distilled away, triphenyl phosphite of about 0.14% relative        to the amount of glycol acid aqueous solution was added. After 5        minutes, antimony trioxide and ethylene glycol were added by        about 0.13% and about 0.5% 7, respectively, relative to the        amount of glycol acid aqueous solution, temperature and degree        of vacuum were further raised while stirring, when a reaction        product started solidifying at 200° C. and 5.0×10⁻⁴ MPa, a        stirring rod was lifted above the reaction fluid level, further,        reaction was carried out till the reaction product was        completely solidified. After completion of reaction, the        reaction product was cooled to room temperature under nitrogen        atmosphere, and pulverized into a powder state. This low polymer        pulverized was subjected to polycondensation reaction at 200° C.        and 5.0×10⁻⁴ MPa for 40 hours, thereby obtaining a polyglycol        acid of pale yellow being almost not colored. Additionally, the        polyglycol acid obtained was used to make a solution of 0.5 g/dl        in concentration with a mixed solvent of        phenol/2,4,5-trichlorophenol (10/7 (weight ratio)), using an        Ubbelohde type viscometer, ηsp/C at 30.0±0.1° C. was obtained to        find 0.63. From ¹H-NMR analysis of this polymer, it was able to        be confirmed that 0.004 mole of ethylene glycol unit was        contained in a molecular chain of polymer relative to 1 mole of        glycol acid unit.)    -   Resin (B-4): Polylactic acid (weight-average molecular weight of        50000, L body of 95%)    -   Resin (B-5): Ethylene vinyl alcohol resin (Kuraray Co., Ltd.,        “Eval”)    -   Film (C-1): Polyethylene film (manufactured by Toray Industries,        Inc., “Toretex”)    -   Film (C-2): Polypropylene film (manufactured by Toray        Industries, Inc., “Torefan BO”)    -   Metal (M-1): Aluminum (manufactured by Nippon Light Metal Co.,        Ltd., “high-purity aluminum wire”)    -   Primer (P-1): Acrylonitrile type coating agent

Example 1

Using a tandem type extruder equipped with a supply line ofsupercritical carbon dioxide, pellets of resin (A-1) and resin (A-2)were mixed in a ratio of Table, and supplied to the first extruder,melted at 220° C., then, supercritical carbon dioxide was supplied atthe tip of the extruder. Next, this was cooled down to 170° C. by thesecond extruder, and extruded into air through a slit die of 10 cm long,thereby to obtain a resin foam of 10 mm thick. Carbon dioxide solubilityin resin (A-1) was 5.5%, and carbon dioxide solubility in resin (A-2)was 3.7%.

The evaluation result of the resin foam is shown in Table 2. Porosity(X) was 97%, the number density of cell (L) was 10⁶/mm², and the numberdensity of cell (S) was 10⁶/μm².

Next, resin (B-1) was supplied to a single screw extruder, heated at 160to 280° C., and extruded in a sheet-shape through a T-die. The sheetextruded was wound around a mirror-surface drum of a temperature of 20°C. to be cooled and solidified, and drawn by 3 times in the longitudinaldirection using a drawing roll of a preheating temperature of 80° C. anda drawing temperature of 100° C., then, drawn by 3 times in the widthdirection using a tenter of a preheating temperature of 90° C. and aheating temperature of 120° C. Subsequently, while relaxation of 5% wasgiven in the width direction, heat treatment was conducted at atemperature of 180° C. for 10 seconds, obtaining a resin film.

Next, in 40 weight % compost sampled from compost including microbehaving biodegradability, 20 weight % polylactic acid emulsion and 40weight % warm water of 30° C. were put, stirred for 24 hours, andfiltrated in several installments. Next, starch of the same weight asthat of filtrate was added to give an adhesive aqueous solution.

Two pieces of film that the above-described aqueous solution wasuniformly coated on non-vapor metallized surface of a resin film havinga vapor deposition layer were prepared, and stuck to a resin foam likewrapping up.

A carbon dioxide gas/water vapor barrier film run of from four cornersof the resin foam was subjected to thermal adhesion with an impulsesealer to give a heat insulating material.

The evaluation result of the heat insulating material obtained is shownin Table 3.

Example 2

Using resin (A-1) and resin (A-3), a resin foam of 10 mm thick wasobtained by extrusion blowing in the same way as Example 1. Carbondioxide solubility in resin (A-1) was 5.5%, and carbon dioxidesolubility in resin (A-3) was 9.0%. The evaluation result of the resinfoam is shown in Table 2. Porosity (X) was 95%, the number density (L)was 10⁶/mm², and the number density (S) was 10⁵/μm².

Next, in an extruder A equipped with a two layer lamination pinole justbefore a T-die, pellets of resin (B-1) and resin (B-2) were mixed by aratio of 40:60 in weight ratio and supplied. Next, resin (B-3) wassupplied to an extruder B linked the pinole with a short pipe. Theextruder A and B were heated at 160 to 280° C. and at 160 to 240° C.,respectively, and a sheet was extruded through the T-die for thelamination ratio (thickness) to be 4:1 in extruder A and B. The sheetextruded was wound around a mirror-surface drum of a temperature of 20°C. to be cooled and solidified, and drawn by 3 times in the longitudinaldirection using a drawing roll of a preheating temperature of 50° C. anda drawing temperature of 55° C., then, drawn by 3 times in the widthdirection using a tenter of a preheating temperature of 50° C. and adrawing temperature of 53° C. Subsequently, while relaxation of 5% wasgiven in the width direction, heat treatment was conducted at atemperature of 180° C. for 10 seconds, obtaining a biaxially drawn film.

The film was subjected to corona treatment of 30 W·min/m² while a filmtemperature was kept at 55° C. under a mixed gas atmosphere of nitrogenand carbon dioxide gas (carbon dioxide gas concentration ratio of 15volume %), and wound up. This was set in a vacuum evaporation apparatusequipped with a film travelling device, and travelled via a coolingmetal drum of 20° C. after setting to a highly reduced pressure sate of1.00×10⁻² Pa. In this time, metal (M-1) was heated and evaporated, and avapor deposition thin film layer was formed on the surface where resin(B-3) was laminated. After vapor deposition, the inside of vaporevaporation apparatus was returned to ambient pressure, the film woundup was rewound, and aged at a temperature of 40° C. for 2 days to obtaina resin film with a vapor deposition layer. Additionally, opticalconcentration of a metal layer was confirmed in-line during vapordeposition, and control was done for the optical concentration to be2.5. The thickness of the resulting resin film with a vapor depositionlayer was 20 μm.

For covering the above-described resin foam with the resin film, twopieces of the resin film trimmed to 15 cm square and the resin foam cutto 10 cm square were prepared. Next, the resin films were set in theopposite side of vapor deposition surface, namely, in such a way thatthe surfaces of finely dispersed layer of resin (B-1) and resin (B-2)faced each other, and the three sides of four sides were subjected tothermal adhesion with an impulse sealer, giving a bag-shape. The widthof thermal adhesion was set to 1 cm from the edge of film. Next, afterthe resin foam was put therein from one side not subjected to thermaladhesion, a heat insulating material was made immediately by conductingthermal adhesion with an impulse sealer to be closely sealed.Additionally, regarding the resin foam used, a resin foam right afterblowing was used, so the above-described sealing operation was donequickly.

The evaluation result of the heat insulating material obtained is shownin Table 3.

Example 3

Using resin (A-1) and resin (A-4), a resin foam of 15 mm thick wasobtained by extrusion blowing in the same way as Example 1. Carbondioxide solubility in resin (A-1) was 5.5%, and carbon dioxidesolubility in resin (A-4) was 3.0%. The evaluation result of the resinfoam is shown in Table 2. Porosity (X) was 84%, the number density ofcell (L) was 10⁴/mm², and the number density of cell (S) was 10³/μm².

Next, resin (B-1) was supplied to a single screw extruder, and abiaxially drawn film was obtained in the same manner as Example 1.

Metal (M-1) was deposited on film (C-2) in the same method as in Example2 to obtain a vapor deposition film. Next, primer (P-1) was coated onthe vapor metallized surface of the vapor deposition film, and stuck tothe biaxially drawn film by dry lamination to give a resin film.

Using the resin foam and resin film obtained, a heat insulating materialwas obtained in the same way as Example 2.

The evaluation result of the heat insulating material obtained is shownin Table 3.

Example 4

Using resin (A-1) and resin (A-3), a resin foam of 10 mm thick wasobtained by extrusion blowing in the same way as Example 1. Theevaluation result of the resin foam is shown in Table 2. Porosity (X)was 95%, the number density (L) was 10⁶/mm², and the number density (S)was 10⁵/μm².

Next, after a biaxially drawn film of resin (B-1) was obtained using asingle screw extruder in the same way as Example 1, metal (M-1) wasdeposited on one surface thereof in the same method as in Example 2 toobtain to obtain a resin film.

Using the resin foam and resin film obtained, a heat insulating materialwas obtained in the same method as in Example 2.

The evaluation result of the heat insulating material obtained is shownin Table 3.

Example 5

A resin foam was obtained in the same method as in Example 4.

Next, using resin (B-3), being drawn by 3 times in the longitudinaldirection using a drawing roll at a preheating temperature of 60° C. anda drawing temperature of 70° C., immediately cooled to room temperature,and drawn by 3 times in the width direction using a tenter at apreheating temperature of 65° C. and a drawing temperature of 80° C.,subsequently, subjected to heat treatment at a temperature of 85° C. for10 seconds while relaxation of 5% was given in the width direction,thereby a biaxially drawn film was obtained. A heat insulating materialwas obtained in the same method as in Example 1 in regard to otherpoints.

The evaluation result of the heat insulating material obtained is shownin Table 3.

Example 6

Using resin (A-1) and resin (A-4), a resin foam of 10 mm thick wasobtained by extrusion blowing in the same way as Example 1. Theevaluation result of the resin foam is shown in Table 2. Porosity (X)was 81%, the number density (L) was 10³/mm², and the number density (S)was 10¹/μm².

Next, using resin (B-5), being drawn by 3 times in the longitudinaldirection using a drawing roll at a preheating temperature of 50° C. anda drawing temperature of 70° C., immediately cooled to room temperature,and drawn by 3 times in the width direction, using a tenter at apreheating temperature of 90° C. and a drawing temperature of 120° C.,subsequently, subjected to heat treatment at a temperature of 160° C.for 10 seconds while relaxation of 5% was given in the width direction,thereby a biaxially drawn film was obtained.

A heat insulating material was obtained in the same method as in Example1 in regard to other points.

The evaluation result of the heat insulating material obtained is shownin Table 3

Example 7

Resin (A-1), resin (A-5) and resin (A-6) were blended in a ratio ofTable, to 100 parts by weight thereof, 5 parts by weight of foamnucleating agent (T-1) was added, and supplied to a tandem type extruderequipped with a supply line of supercritical carbon dioxide. Afterheat-melting at 180 to 220° C. in the first extruder, supercriticalcarbon dioxide was supplied. Subsequently, this was cooled down to 120to 170° C. by the second extruder, and extruded into air through a slitdie of 10 cm long, thereby to obtain a resin foam of 10 mm thick.Additionally, carbon dioxide solubility in resin (A-1) was 5.5%, carbondioxide solubility in resin (A-5) was 9%, and carbon dioxide solubilityin resin (A-6) was 3.7%. The distributed domain of resin (A-5) was 0.01to 0.02 μm from TEM observation after OsO4 dying. The evaluation resultof the resin foam obtained is shown in Table 2. SEM pictures of crosssection of the resin foam are shown in FIG. 4 to FIG. 6. Porosity (X)was 97%, the number density (L) was 10³/mm², and the number density (S)was 10³/μm².

Next, a vapor deposition film was obtained in the same way as Example 2.Thereafter, primer (P-1) was coated on the resin surface opposite to thevapor metallized surface of the vapor deposition film obtained, film(C-2) was stuck on the vapor metallized surface and film (C-1) was stuckon the resin surface by dry lamination, thereby to give a resin film.

For covering the above-described resin foam with the resin film, twopieces of the resin film trimmed to 15 cm square and the resin foam cutto 10 cm square were prepared. Next, a bag-shape was made in such amanner that the surfaces of film (C-1) faced each other and, the threesides of four sides were subjected to thermal adhesion with an impulsesealer. The width of thermal adhesion was set to 1 cm from the edge offilm. Next, after the resin foam was put therein from one side notsubjected to thermal adhesion, a heat insulating material was madeimmediately by conducting thermal adhesion with an impulse sealer to beclosely sealed. Additionally, regarding the resin foam used, a resinfoam right after blowing was used, so the above-described sealingoperation was done quickly.

The evaluation result of the heat insulating material obtained is shownin Table 3.

Example 8

Resin (A-1), resin (A-5) and resin (A-8) were blended in a ratio ofTable, to 100 parts by weight thereof, 5 parts by weight of foamnucleating agent (T-1) was added, a resin foam was obtained in the samemethod as in Example 7. Additionally, the distributed domain of resin(A-5) was 0.01 to 0.03 μm from TEM observation after OsO4 dying.

The evaluation result of the resin foam obtained is shown in Table 2.Porosity (X) was 93%, the number density (L) was 10²/mm², and the numberdensity (S) was 10³/μm².

Next, using resin (B-5), being drawn by 3 times in the longitudinaldirection using a drawing roll at a preheating temperature of 50° C. anda drawing temperature of 70° C., immediately cooled to room temperature,and drawn by 3 times in the width direction using a tenter at apreheating temperature of 90° C. and a drawing temperature of 120° C.,subsequently, subjected to heat treatment at a temperature of 160° C.for 10 seconds while relaxation of 5% was given in the width direction,thereby a biaxially drawn film was obtained. In regard to this biaxiallydrawn film obtained, metal (M-1) deposition was conducted in the samemethod as in Example 7 to obtain a vapor deposition film. Next, in thesame method as in Example 7, film (C-1) and film (C-2) were stuckthereon by dry lamination to give a resin film.

By covering the above-described resin foam with the resin film in thesame method as in Example 7, a heat insulating material was made.

The evaluation result of the heat insulating material obtained is shownin Table 3.

Example 9

Resin (A-4), resin (A-6) and resin (A-8) were blended in a ratio ofTable, to 100 parts by weight thereof, 5 parts by weight of foamnucleating agent (T-1) was added, a resin foam was obtained in the samemethod as in Example 7, and the resin foam was evaluated for thermalinsulation performance. The evaluation result of the resin foam obtainedis shown in Table 2. Porosity (X) was 93%, the number density (L) was10^(1.8)/mm², and the number density (S) was 10^(1.6)/μm².

Next, metal (M-1) deposition was conducted on film (C-2) in the samemethod as in Example 2 to obtain a resin film.

By covering the above-described resin foam with the resin film in thesame method as in Example 7, a heat insulating material was made.

The evaluation result of the heat insulating material obtained is shownin Table 3.

Comparative Example 1

Using a tandem type extruder equipped with a supply line ofsupercritical carbon dioxide, resin (A-3) and resin (A-4) were mixed ina ratio of Table, and supplied to the first extruder, melted at 200 to220° C., then, supercritical carbon dioxide was supplied at the tip ofthe extruder. Next, this was cooled down to 120 to 170° C. by the secondextruder, and extruded into air through a slit die of 10 cm long,thereby to obtain a resin foam of 10 mm thick. Additionally, carbondioxide solubility in resin (A-3) was 9.0%, and carbon dioxidesolubility in resin (A-4) was 3.0%. The distributed domain of resin(A-3) was 2.0 to 10 μm from TEM observation after OsO4 dying. Theevaluation result of the resin foam obtained is shown in Table 4.

Next, a vapor deposition film and a heat insulating material wereobtained in the same way as Example 2.

The evaluation result of the heat insulating material obtained is shownin Table 5.

Comparative Example 2

To 100 parts by weight of resin (A-4), 5 parts by weight of foamnucleating agent (T-1) was added, using a tandem type extruder equippedwith a supply line of supercritical carbon dioxide, a resin foam wasobtained in the same method as in Comparative Example 1. The evaluationresult of the resin foam obtained is shown in Table 4.

Next, resin (B-1) was supplied to a single screw extruder, and abiaxially drawn film was obtained in the same way as ComparativeExample 1. Next, metal (M-1) deposition was conducted on film (C-2) inthe same method as in Comparative Example 1 to obtain a vapor depositionfilm. Next, primer (P-1) was coated on the vapor metallized surface ofthe vapor deposition film, and stuck to the above-described biaxiallydrawn film by dry lamination to give a resin film.

By covering the resin foam obtained with the resin film in the samemethod as in Comparative Example 1, a heat insulating material wasobtained.

The evaluation result of the heat insulating material obtained is shownin Table 5.

Comparative Example 3

Resin (A-3) and resin (A-7) were kneaded in a ratio of Table by abiaxial extruder to obtain strand chips. Using the strand chipsobtained, they were blown in the same method as in ComparativeExample 1. Next, for the purpose of removing resin (A-3), the foam wassoaked in warm water of 40° C., stirred for 10 minutes, then, taken outfrom warm water, and sufficiently dried to obtain a resin foam.Additionally, carbon dioxide solubility in resin (A-3) was 9.0%, andcarbon dioxide solubility in resin (A-7) was 7%. Dispersion diameter ofresin (A-3) was 0.5 μm. The evaluation result of the resin foam obtainedis shown in Table 4.

Next, a resin film was obtained in the same way as Example 1.

For covering the above-described resin foam with the resin film, twopieces of the resin film trimmed to 15 cm square and the resin foam cutto 10 cm square were prepared. Next, a bag-shape was made in such mannerthat the three sides of four sides of the resin film were subjected tothermal adhesion with an impulse sealer. The width of thermal adhesionwas set to 1 cm from the edge of film. Next, after the resin foam wasput therein from one side not subjected to thermal adhesion, a heatinsulating material was made immediately by conducting thermal adhesionwith an impulse sealer to be closely sealed. Additionally, regarding theresin foam used, a resin foam right after blowing was used, so theabove-described sealing operation was done quickly.

The evaluation result of the heat insulating material obtained is shownin Table 5.

Comparative Example 4

Resin (A-3) and resin (A-7) were kneaded in a ratio of Table by abiaxial extruder to obtain strand chips. Using the strand chipsobtained, they were blown in the same method as in Comparative Example3. Next, for the purpose of removing resin (A-3), the foam was soaked inwarm water of 40° C., stirred for 10 minutes, then, taken out from warmwater, and sufficiently dried to obtain a resin foam. Additionally,dispersion diameter of resin (A-3) was 3 μm. The evaluation result ofthe resin foam obtained is shown in Table 4.

Comparative Example 5

In place of resin foam, fiber-based heat insulating material (GW-1) wasused. The fiber-based heat insulating material (GW-1) was covered byusing film (C-1) in the same method as in Comparative Example 1.

TABLE 2 Example Example Example Example Example Example Example Example1 2 3 4 5 6 7 8 Resin Resin(A-1) Weight % 80 80 60 80 80 50 75 75 foamResin(A-2) Weight % 20 — — — — — — — Resin(A-3) Weight % — 20 — 20 20 —— — Resin(A-4) Weight % — — 40 — — 50 — — Resin(A-5) Weight % — — — — ——  5  5 Resin(A-6) Weight % — — — — — — 20 — Resin(A-7) Weight % — — — —— — — — Resin(A-8) Weight % — — — — — — — 20 Fiber-based heat Weight % —— — — — — — — insulating material (GW-1) Blowing agent (F-1) Weight %  7 7  7  7  7  7  7  7 Foam nucleating agent Part by — — — — — —  5  5(T-1) weight Porosity (X) % 97 95 84 95 95 81 97 93 Porosity (X2) % 97 —— — — — 97 95 Cell (L) number density Pieces/mm²  10⁶  10⁶  10⁴  10⁶ 10⁶  10³  10³  10² Cell (S) number density Pieces/μm²  10⁶  10⁵  10³ 10⁵  10⁵  10¹  10³  10³ Cell size distribution μm 10 10 10 10 10 50 50100  (peak 1) Cell size distribution μm    0.01    0.01    0.02    0.01   0.01    0.10    0.02    0.05 (peak 2) Thermal insulation mW/mK   27.0  27.0   29.0   27.0   27.0   29.5   27.0   27.5 performance

TABLE 3 Example Example Example Example Example Example Example Example1 2 3 4 5 6 7 8 Resin Resin(B-1) ∘ ∘ ∘ ∘ — — ∘ — film Resin(B-2) — ∘ — —— — ∘ — Resin(B-3) — ∘ — — ∘ — ∘ — Resin(B-4) — — — — — — — — Resin(B-5)— — — — — ∘ — ∘ Film (C-1) — — — — — — ∘ ∘ Film (C-2) — — ∘ — — — ∘ ∘Metal (M-1) — Al Al Al — — Al Al Primer (P-1) — — ∘ — — — ∘ ∘ Filmthickness μm 10 20 20 20 20 20 21 21 Lamination Lamination 1 2 2 1 1 1 43 number of number resin film Carbon dioxide Volume % 80 80 80 80 80 8080 80 gas volume Carbon dioxide mL/ 12.0 0.1 1.6 4.2 1.0 0.9 0.07 0.10gas permeability (m² · atm · day) Water vapor g/ 18.0 2.0 3.0 4.9 4.84.5 1.2 1.00 permeability (m² · day) Thermal Right after mW/mK 24.0 21.022.0 23.5 22.0 22.0 21.0 21.0 conductivity production Aging test (1)mW/mK 30.0 22.5 23.5 25.5 24.0 23.0 21.5 22.5 Aging test (2) mW/mK 32.023.0 23.5 26.0 24.5 24.0 22.0 23.0 Condensation Condensation JISA 1514 Δ∘ ∘ ∘ ∘ ∘ ∘ ∘ test preventing performance Wall x ∘ ∘ ∘ ∘ ∘ ∘ ∘condensation preventing test

TABLE 4 Comparative Comparative Comparative Comparative ComparativeExample 1 Example 2 Example 3 Example 4 Example 5 Resin Resin(A-1)Weight % — — — — — foam Resin(A-2) Weight % — — — — — Resin(A-3) Weight% 10 — 1 5 — Resin(A-4) Weight % 90 100 — — — Resin(A-5) Weight % — — —— — Resin(A-6) Weight % — — — — — Resin(A-7) Weight % — — 99  95  —Resin(A-8) Weight % — — — — — Fiber-based heat Weight % — — — — 100insulating material (GW-1) Blowing agent (F-1) Weight %  7  7 7 7 — Foamnucleating Part by weight —  5 — — — agent (T-1) Porosity (X) % 85  9360  60   90 Porosity (X2) % — — — — — Cell (L) number Pieces/mm² — — 106 10 4.6 — density Cell (S) number Pieces/μm² — — 1 — — density Cellsize distribution μm 500  600 1 5 — (peak 1) Cell size distribution μm  20.0 —   0.5 — — (peak 2) Thermal insulation mW/mK   38.0   33.0  42.0   42.0   35.0 performance

TABLE 5 Comparative Comparative Comparative Comparative ComparativeExample 1 Example 2 Example 3 Example 4 Example 5 Resin Resin(B-1) ∘ ∘ ∘— — film Resin(B-2) ∘ — — — — Resin(B-3) ∘ — — — — Resin(B-4) — — — — —Resin(B-5) — — — — — Film (C-1) — — — — ∘ Film (C-2) — ∘ — — — Metal(M-1) Al Al — — — Primer (P-1) — ∘ — — — Film thickness μm 20 20 20 — 20Lamination Lamination 2 2 1 — 1 number of number resin film Carbondioxide Volume % 80 80 5 — 5 gas volume Carbon dioxide mL/ 0.05 0.9 12.0— 24.0 gas permeability (m² · atm · day) Water vapor g/ 1.0 1.2 35.0 —11.0 permeability (m² · day) Thermal Right after mW/mK 32.0 30.0 40.0 —36.0 conductivity production Aging test (1) mW/mK 32.5 30.5 41.5 — 36.0Aging teat (2) mW/mK 33.0 31.0 42.0 — 36.5 Condensation CondensationJISA 1514 ∘ ∘ x — Δ test preventing performance Wall ∘ ∘ x — xcondensation preventing test

1. A resin foam having a porosity (X) of not less than 80%, a cell (L)with a cell diameter of not less than 1 μm and not more than 1000 μm,and a cell (S) with a cell diameter of not less than 0.01 μm and lessthan 1 μm.
 2. The resin foam described in claim 1, wherein a numberdensity of the cell (L) is not less than 10²/mm² and not more than10⁷/mm², and a number density of the cell (S) is not less than 10²/μm²and not more than 10⁷/μm².
 3. The resin foam described in claim 1,wherein two peaks are present in the cell size distribution, one peakthereof is present in not less than 10 μm and not more than 500 μm, andanother peak is present in not less than 0.01 μm and less than 1 μm. 4.The resin foam described in claim 1, comprising a biodegradablepolyester resin, and at least one kind of resin selected from the groupconsisting of a polyether-polylactic acid block copolymer, apolypropylene resin, a methacrylic resin, anacrylonitrile-butadiene-styrene resin and a polyester resin differentfrom the biodegradable polyester resin.
 5. A heat insulating materialcomprising the resin foam described in claim 1, carbon dioxide gas and aresin film, wherein the resin film is not more than 15 [mL/(m²·day·atm)](23° C., 0% RH) in carbon dioxide gas permeability, covering the resinfoam and the carbon dioxide gas.
 6. The heat insulating materialdescribed in claim 5, wherein a concentration of internal carbon dioxidegas covered by the resin film is not less than 50% by volume.
 7. Theheat insulating material described in claim 5, wherein the carbondioxide gas is derived from carbon dioxide of a blowing agent.
 8. Theheat insulating material described in claim 7, wherein the carbondioxide is carbon dioxide in a supercritical state.
 9. The heatinsulating material described in claim 5, wherein the resin filmincludes a biodegradable polyester resin.
 10. The resin foam describedin claim 2, wherein two peaks are present in the cell size distribution,one peak thereof is present in not less than 10 μm and not more than 500μm, and another peak is present in not less than 0.01 μm and less than 1μm.
 11. The resin foam described in claim 2, comprising a biodegradablepolyester resin, and at least one kind of resin selected from the groupconsisting of a polyether-polylactic acid block copolymer, apolypropylene resin, a methacrylic resin, anacrylonitrile-butadiene-styrene resin and a polyester resin differentfrom the biodegradable polyester resin.
 12. The resin foam described inclaim 3, comprising a biodegradable polyester resin, and at least onekind of resin selected from the group consisting of apolyether-polylactic acid block copolymer, a polypropylene resin, amethacrylic resin, an acrylonitrile-butadiene-styrene resin and apolyester resin different from the biodegradable polyester resin.
 13. Aheat insulating material comprising the resin foam described in claim 2,carbon dioxide gas and a resin film, wherein the resin film is not morethan 15 [mL/(m²·day·atm)] (23° C., 0% RH) in carbon dioxide gaspermeability, covering the resin foam and the carbon dioxide gas.
 14. Aheat insulating material comprising the resin foam described in claim 3,carbon dioxide gas and a resin film, wherein the resin film is not morethan 15 [mL/(m²·day·atm)] (23° C., 0% RH) in carbon dioxide gaspermeability, covering the resin foam and the carbon dioxide gas.
 15. Aheat insulating material comprising the resin foam described in claim 4,carbon dioxide gas and a resin film, wherein the resin film is not morethan 15 [mL/(m²·day·atm)] (23° C., 0% RH) in catbon dioxide gaspermeability, covering the resin foam and the carbon dioxide gas. 16.The heat insulating material described in claim 6, wherein the carbondioxide gas is derived from carbon dioxide of a blowing agent.
 17. Theheat insulating material described in claim 6, wherein the resin filmincludes a biodegradable polyester resin.
 18. The heat insulatingmaterial described in claim 7, wherein the resin film includes abiodegradable polyester resin.
 19. The heat insulating materialdescribed in claim 8, wherein the resin film includes a biodegradablepolyester resin.